Conventional pin-tumbler cylinder locks comprise a cylinder having a series of pins which are actuated in a well known manner by a key having matching serrations, to lock and unlock the same. These locks are usually made of relatively soft, non-ferrous metals because of the low corrosion and self-lubricating characteristics thereof. The design of most locks is such that the tumbler-lifting key serrations and the tumbler pins of the lock must be closely aligned in order to effect ready turning of the key in the lock cylinder for lifting the tumblers. Keys are conventionally provided with a shoulder or stop for engaging the face of the lock when the key has been inserted into the lock to a depth to effect the alignment of the key serrations and tumbler pins.
Due to the softness of the metals employed for the key and the lock, rapid wear occurs at the bearing point of the key shoulder and the lock. This produces misalignment between the key serrations and the tumbler pins producing difficulties in attempting to actuate the lock. A new key will not correct this condition since the wear occurs on the face of the lock cylinder as well as the key itself. Therefore, when this occurs, it has been standard practice to discard the entire lock cylinder and key and install a replacement.
It is an object of this invention to provide a key locating attachment for controlling the depth of penetration of a key into a lock in order to effect alignment between the operating parts of the key and the lock for repeatedly actuating the same with ease.
Another object is to provide an attachment of the character described wherein the attachment is longitudinally movably mounted on a key in order to adjust the working depth of entry thereof into the lock to compensate for wearing of parts of the key and lock.
A further object is to provide an attachment of the character described which is of simple, economic construction, and which may be readily attached to a standard key.
Other objects will be apparent from the following description of the presently preferred forms of this invention taken together with the appended drawings.